Department of Meteorology ST1.3 Atmospheric Precursors Adrian Champion*, Richard Allan (UoR) Hayley Fowler, Stephen Blenkinsop (UoN) 1/26/20 University of Reading 2008 www.reading.ac.uk Deliverables & Milestones M1.3.1 Identification of precursors and
time/space scales of FFIR events (M12) M1.3.2 Identification of clusters of events and links to catchment types (M24) D1.3.1 Development of a case study set for WT2 intercomparison experiments (M33) D1.3.2 Peer reviewed articles for J. Clim., JGR (M36) Annual SINATRA Meeting, Newcastle University, November 2014 2 M1.3.1 Identification of Precursors Lavers et al. (2011, 2012) linked narrow bands of moisture convergence (Atmospheric Rivers)
to winter flooding in the North-West of England. Atmospheric River defined using vertically integrated horizontal water vapour transport (IVT), present for 18 hours, extending over 2000km, using a threshold approach. Annual SINATRA Meeting, Newcastle University, November 2014 3 Champion et al., sub. Atmospheric River
Annual SINATRA Meeting, Newcastle University, November 2014 4 Atmospheric River Annual SINATRA Meeting, Newcastle University, November 2014 5 ARs & Summer Extreme Rain Daily raingauge data from MIDAS 90% threshold of UK daily rain ERA-Interim (1979 - 2013) & 20CR (1900
2012) Summer results: <20% of extreme rain events identified had an associated AR. <10% of ARs produce an extreme rain event. Champion, A.J., Allan, R.P., Lavers, D.A., sub.: Atmospheric Rivers University, dont explain UK2014 Summer Extreme6 Annual SINATRA Meeting, Newcastle November Champion et al.,
sub. ARs and Summer Extreme Rain Annual SINATRA Meeting, Newcastle University, November 2014 7 MSc Dissertation Student Maya Balasubramanyam Extreme Rainfall and the Relationship to Summer Flooding Events in the UK Sponsored by Catlin Group (re-insurance company)
Investigated different thresholds to define a rain event as an extreme rain event 1900 2013 Comprehensive comparison to literature (newspapers, data sources) Use of extreme value theory to investigate trends Looked at the atmospheric conditions prior to some of the identified events Highlight role of CAPE Annual SINATRA Meeting, Newcastle University, November 2014 8 Balasubramanyam, 2014. MSc
Dissertation MSc Student Dissertation Annual SINATRA Meeting, Newcastle University, November 2014 9 Balasubramanyam, 2014. MSc Dissertation MSc Student Dissertation 18 16 14
Number of events 12 10 Frontal Convective 8 6 4 2 0 A
B C D E Region Annual SINATRA Meeting, Newcastle University, November 2014 10 New Identification Methods
Time-integrated variables: IVT Specific humidity More localised processes: Vertical velocity New tracking method: WCB within extra-tropical cyclones Annual SINATRA Meeting, Newcastle University, November 2014 11 Early Investigations
Annual SINATRA Meeting, Newcastle University, November 2014 12 clusters of events and links to catchment types Use hourly raingauge dataset being produced by Newcastle University (Stephen Blenkinsop) Combine with results from precursor study to identify atmospheric events. Annual SINATRA Meeting, Newcastle University, November 2014
13 Summary M1.3.1 Extension of AR work by Lavers et al. showed very little correlation between ARs and summer FFIR events New metrics currently being tested with a view of looking at more localised processes M1.3.2 Will start middle of next year. D1.3.1 Collaboration with Newcastle University using hourly raingauge dataset
D.1.3.2 Paper on linking ARs to summer FFIR events submitted to JGR. Annual SINATRA Meeting, Newcastle University, November 2014 14 Extra Slides Annual SINATRA Meeting, Newcastle University, November 2014 15 items from this subtask of interest for EA/SEPA/FFC/Met
Office Patterns associated with extreme events Moisture transports Moisture distribution SST patterns, CAPE Physical processes associated with extreme events Annual SINATRA Meeting, Newcastle University, November 2014 16 criteria of 'measure of success'
to work towards (e.g. impact) Papers of broad interest Media interviews Identification of drivers Annual SINATRA Meeting, Newcastle University, November 2014 17 Atmospheric precursors in GPCP-1DD and model Example column integrated or 850 hPa moisture and vapour transport precursors
Annual SINATRA Meeting, Newcastle University, November 2014 18 Number of heaviest 1% of rainfall events by month Sum over all grid points around the British Isles Distinct daily rainfall events only (no duplicates) Less heavy daily rainfall observed in summer Model simulates fewer distinct events in spring
Annual SINATRA Meeting, Newcastle University, November 2014 19 Example moisture and transport fields prior to daily event GPCP/ERA Interim HadGEM2-A Heaviest daily event
Annual SINATRA Meeting, Newcastle University, November 2014 Composit e moisture fields over top 1% of20 Example moisture and transport fields prior to JJA daily event GPCP/ERA Interim HadGEM2-A
Heaviest daily event Annual SINATRA Meeting, Newcastle University, November 2014 Composit e moisture fields over top 1% of21
